The purpose of this study is to identify a cohort of children and adolescents who are at significant risk for developing anxiety disorders. The study will define the expression of the risk for anxiety disorder and identify critical factors in the development of the adult syndrome. The data will demonstrate that children of adults with anxiety disorders have an increase of general clinical disturbance and, specifically, increased frequency of diagnosis of anxiety disorders of childhood and adolescence. The study will also identify the association of biological markers, with anxiety disorders in children and adults, including exercise intolerance with abnormal lactate metabolism, mitral valve prolapse, and increased autonomic tone. The course of children who are at risk will be followed in order to demonstrate an increased onset of adult anxiety disorders following pubescence, and the relationship between anxiety disorders, depression and alcoholism and drug abuse. In addition the study will investigate the relationship of family and psychosocial stressors to the onset of anxiety disorders. Adult drug study subjects and their children will be evaluated for diagnosis of anxiety disorder. State, trait and personality measures will be used, including structured psychiatric interview, MMPI, Personality Inventory for Children, and Fear Survey Schedules. Additional data will be collected on adult subjects' developmental history and family incidence of anxiety and related disorders. Children and adults will receive a complete cardiac evaluation for mitral valve prolapse. Lactate will be serially measured in children and adults during exercise tolerance testing to assess the association of lactate metabolism to anxiety disorder. Adult subjects will additionally receive infusion of lactate to assess its relationship to onset of panic attacks. Despite the strong familial pattern of transmission, these disorders have not been systematically studied in children, and the relationship between fears and anxiety in childhood and the adult disorders is not understood. This study will provide a model for the study of genetic, biological and psychosocial factors in childhood psychopathology, and provide a basis for the early identification and preventive treatment of problems in children.